def main():
"""creates an instance of Airport and tests all the functions
"""
airport = Airport('Vancouver Regional Airport', 4)
cap = CapacityObserver(airport)
air = AirplaneObserver(airport)
airport.attatch_observer(air)
airport.attatch_observer(cap)
airport.land_airplane('A0001')
airport.land_airplane('A0002')
airport.land_airplane('B0011')
airport.land_airplane('B0012')
airport.set_max_capacity(15)
print('%s current maximum capacity is %s' %
(airport.get_airport_name(), airport.get_max_capacity()))
airport.set_max_capacity(8)
airport.depart_airplane('B0012')
airport.depart_airplane('B0011')
airport.depart_airplane('A0002')
airport.depart_airplane('A0001')
print(str(airport))
